Accurate time configuration is vital for the Screenly Player security and playback features to function.
Screenly Player uses the world's standard method to coordinate the time - Network Time Protocol.
On most networks NTP services will work by default, however, sometimes additional steps are required to enable it. In the case of an unstable connection, you can add fallback services using the Screenly Configuration Wizard found at https://wizard.screenly.io. Select the "Screenly 2 Player" option, select the "Configure NTP setting" option and add more NTP servers which you can get from https://www.ntppool.org.
In corporate networks with firewalls you either need to whitelist ntp.ubuntu.com to make NTP work or make Screenly Player use the NTP service from your network by configuring it with https://wizard.screenly.io.
Here are the Screenly network requirements.